The present invention pertains generally to a system and equipment enabling the drive on loading and drive off unloading of trucks from a flat bed railway car.
Well known is the practice of transporting truck trailers by loading same onto specially modified railway cars. Such transport of trailers is termed piggyback in the trade. An important drawback to the shipping of truck trailers by piggyback is the man hour effort in the loading and off loading of the trailers and the support equipment required to accomplish same.
German patent application DE 3425698A1 published Jan. 23, 1986, discloses a truck tractor and trailer equipped with auxiliary undercarriages for lateral travel of both the truck tractor and attached trailer during loading onto a railway car equipped with a side mounted ramp. Accordingly it has been proposed to ship both truck tractor and trailer as a unit on a railway car.
U.S. Pat. No. 4,964,767 discloses the stabilizing of a stationary flat bed railway car by car components extensibily engageable with the edge structure of a loading dock to prevent lateral tipping of the car during loading of a truck trailer. The truck tractor is used as a prime mover during such loading and unloading. Various car stabilizing means are disclosed to prevent lateral tipping as the trailer is moved on an auxiliary undercarriage laterally onto the railway car.
U.S. Pat. No. 252,918 is of some interest in that it discloses a railway car truck modified by the addition of glides at the four corners of a car truck. Each glide includes a wheel biased downwardly by a spring to engage a rail located outwardly from a conventional pair of rails. Car weight is, during travel, jointly carried by the wheels of the car truck and by the glides apparently to minimize sound. No loading-unloading purposes are disclosed. The glide carried wheels are carried on the car trucks and could not directly support the car frame against tipping during loading of the car from the side.
Regardless of the readily apparent advantages to the public of transporting truck tractors and their trailers as a unit via rail to distant destinations, no present system is in place or equipment presently available for accomplishing same.